Manually operable devices for spraying a fluid are well known. Such devices range from the Flit gun pump type to the water pistol or trigger variety.
Many of the earliest such devices employed a single-action air pump to provide the force to dispense a powdered material. U.S. Pat. No. 572,907 to Norton, "Poison Distributer", is of this type.
U.S. Pat. No. 243,163 to Schlauch, "Atomizer", discloses a double action pump which pumps air into a reservoir containing a liquid, thus forcing the liquid out a discharge pipe.
U.S. Pat. No. 2,109,589 to Horwitt et al., "Liquid Pistol", discloses a trigger-activated pump incorporated into a pistol-like sprayer for liquid having a handle portion which is a removable container for the liquid to be sprayed.
U.S. Pat. No. 4,204,645 to Hopp, "General Purpose Compression-Type Sprayer", discloses a single action plunger pump which forces air into a chamber and then into a supply tank holding the material to be sprayed. The material is then forced out a passage to a mixer and ejection orifice.
U.S. Pat. No. 3,485,180 to Wickenberg et al., "Double-Acting Pump for Gas or Liquid", discloses a pump formed by a hollow cylinder and having a piston which has a sealing ring around its periphery and a hollow piston rod, the sealing ring movable between two positions. The cylinder has two closed ends with openable fluid access means at each end. The piston divides the cylinder into two chambers and the piston rod extends through one end of the cylinder. The moveable sealing rod, upon relative motion of the piston and cylinder, opens access means in the piston for fluid recess to one chamber or the other.